In a non-human primate model for aging and cerebrovascular disease, the interactive effect of normal aging and induced systolic hypertension will be investigated. This investigation will employ clinically available neuroimaging techniques to examine the brains of young and middle-aged rhesus monkeys (Macaca mulatta) in vivo. Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS) will be utilized to explore morphologic and metabolic changes, respectively, in the young and middle-aged cohorts. Behavioral tests based on clinically applied neuropsychological measures will determine cognitive ability as well. Following completion of behavioral testing, a surgical procedure to coarct the thoracic aorta will induce systolic hypertension in both cohorts. Post-op examination of the cohorts' brains will be accomplished using methods identical to pre-op procedures-morphological examination using MRI and MRS, and cognitive ability measurement using behavioral tests. Further examination of these brains will be accomplished post- mortem, as soon as behavioral tests are completed. Brain tissue will be stained to reveal morphology, metabolic activity, and microglia reactivity, and will be quantified using optical sampling and stereological methodology. Finally, this investigation will conclude by comparing brain morphology, metabolic activity and cognitive ability between the young and middle-aged cohorts pre- and post-operatively.